Robert Scoble linked to an interview with a "Tablet PC addict" in the San Diego Union-Tribune.
The interviewee (Beth Simon) says she's addicted to Tablet PCs and takes handwritten notes on them. I must admit I've never used a Tablet PC, but I don't get the point of taking handwritten notes on a computer. I'd hazard a guess most people can type quicker than they can actually write (not taking into account the lag that might occur while you write onto the screen and the software interprets it), so what would be the point? (This is coming from the point of view of a student and a programmer. I can see that there are numerous uses for people in graphics, animation, etc.) I'd rather type my notes up than worry about whether the computer is going to recognise my handwriting because I'm frantically trying to record what information is on a lecture slide before the lecturer moves on.
One area in which I think having a Tablet PC would be useful, however, is drawing models or diagrams (which you could possibly include in taking handwritten notes). On a number of occasions I've sat in lectures and wanted to copy down the diagram on the projector or board, and it's just too much of a hassle to open up OmniGraffle. It'd be great to just whip out the pen and while in my note-taking app (currently OmniOutliner) write down an equation or diagram amongst the typed notes.
It would be great for Apple to come out with something like this, but I think the size of the market is so small that it's not worth it. (Microsoft, on the other hand, can afford it.) Of course, I could always just lug around a Wacom tablet, but that's a little cumbersome.
Yes, drawing models and diagrams is a distinct advantage. Also, as Robert suggests, you might try the audio feature in OneNote to record the lectures (if the professor allows that - some don’t because of copyright) and then write the basic outline, graphs, charts, etc. Other applications to consider: Agilix GoBinder, a student note system, and xThink MathJournal, for solving equations.